The present invention relates to a high frequency heating apparatus with steam generation function in which high frequency heating and steam heating are combined to heat-treat an object to be heated.
Traditionally, in this type of high frequency heating apparatus, there are a microwave oven with a high frequency generator for heating, and a combination oven that a convection heater for generating heated air is added in this microwave oven. In addition, a steamer that steam is introduced into a heating chamber and a steam convection oven that a convection heater is added in a steamer are also used as cooking appliances.
When food is cooked by the cooking appliance, the cooking appliance is controlled so as to cook the food in the best condition. More specifically, the cooking of combining high frequency heating with hot air heating can be controlled by the combination oven, and the cooking of combining steam heating with hot air heating can be controlled by the steam convection oven. However, in the cooking of combining high frequency heating with steam heating, efforts are needed that food to be cooked is transferred between different cooking appliances in each of heat treatment. In order to solve the inconvenience, there is a cooking appliance that realizes high frequency heating, steam heating, and electric heating by a single appliance. This cooking appliance is disclosed in JP-A-54-115448.
However, according to the configuration of the publication, a vaporizing chamber for generating heated steam is embedded under a heating chamber, and water is supplied from a water storage tank at a fixed water level all the time. Therefore, it is difficult to clean the periphery of the heating chamber everyday. A problem arises particularly in the vaporizing chamber that calcium and magnesium in water are concentrated to precipitate and fix onto the bottom of the vaporizing chamber or the inside of pipes to reduce an amount of steam generated in the course of generating steam, and consequently the chamber is turned to a dirty environment where mold is easily propagated.
In addition, as a system for introducing steam into the heating chamber, it can be considered that steam is generated by a heating unit such as a boiler disposed outside the heating chamber and the steam generated here is supplied to the heating chamber. However, problems arise that mold is contaminated and propagated in a pipe for introducing steam, the pipe for introducing steam is damaged by freezing, and foreign substances such as rust are mixed. Furthermore, the heating unit is often difficult to be disassembled and cleaned. Therefore, in the cooking appliances that particularly require the attention to the hygiene of food to be treated, the system for introducing steam from outside is hard to adopt.